The present invention relates to satellite communications, and in particular, to partitioned phased array antenna communication systems with improved throughput capacity and reduced weight, size, and power consumption.
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Phased array antennas are capable of steering transmission and reception beams over a small field of view. The ability of phased arrays to steer beams makes them suitable for relay communication systems in which multiple pathways between multiple locations are created (e.g., pathways between an internet service provider gateway and user terminals). The directivity of a phased array antenna is largely determined by the number of antenna elements in the phased array. The better the directivity with which the beams can be steered allows for greater throughput because beams that might otherwise interfere with one another can be physically separated. Two beams with the same or overlapping carrier frequencies or polarizations can be directed toward two geographically isolated regions to avoid interference.
Adding a reflector, such as a parabolic reflector, to the phased array antenna can increase the directivity of the antenna without increasing the number of phased array elements. Phased array antennas configured with reflectors are often referred to as phased array fed reflector (PAFR) antennas. The increase in directivity afforded by PAFR antennas without the addition of size, weight and power consumption associated with additional antenna elements and the underlying beam forming hardware is particularly useful in size, weight, and power constrained devices and systems. For example, the payload and power capacities of satellites used in satellite communication systems are inherently limited. The directivity of a PAFR antenna in a satellite can provide for improved geographic separation of beams. The larger geographic separation of beams provides for increased frequency spectrum reuse and, therefore, increased throughput capacity.
Even with the use of PAFR antennas, the payload and power constraints on the capabilities of phased array antenna satellite communication systems directly impact such systems' data throughput capacity. In a conventional PAFR antenna satellite communication system, the beam forming hardware of the phased array can account for more than two-thirds of the antenna system's size and mass and about a fifth of the system's the power consumption. However, much of the phased array is underutilized or unutilized when the PAFR antenna is aimed off center. Off center beams are typically referred to as being “off bore-sight”. For off bore-sight beams that are directed a few degrees off center, a PAFR antenna might use at little as two-thirds of the antenna elements and beam forming hardware in the array. Accordingly, for many of the beams that a PAFR antenna system is capable of forming, much of the system's hardware is unused. The underutilization of beam forming hardware contributes to size, weight and power consumption based limitations on throughput capacity in satellite communication systems. Throughput capacity limitations contribute to the difficulty satellite communication systems have when competing with other communication and data delivery methods (e.g., digital subscriber lines (DSL), cable, WiMax, etc.). What is needed is a system and method for a phased array antenna that allows for increased throughput capacity without increasing weight, size, or power consumption.